Controlling active isolation platform in a moving vehicle

ABSTRACT

Systems and methods for actively isolating a payload from a disturbance. In one example, a seat system for a vehicle includes a seat, a support structure that allows the seat to move about an axis of a pivot, a first sensor positioned to detect movement of the vehicle, a second sensor positioned to detect lateral acceleration of the pivot, an actuator configured to move the seat, and a controller configured to receive a first signal from the first sensor and a second signal from the second sensor, generate a command signal based at least on the first and the second signal to instruct the actuator to position the seat at a desired command angle, wherein the controller is configured to correct the command signal for lateral accelerations caused by steering the vehicle, and provide a force command to the actuator to move the seat at the desired command angle.

TECHNICAL FIELD

Aspects and implementations of the present disclosure are directedgenerally to payload suspension, and in some examples, more specificallyto vehicle seats and methods for actively isolating a payload fromvehicle movement.

BACKGROUND

In a Cartesian coordinate system (x, y, and z directions) a payload heldby a platform may be subject to motion in various directions. Forexample, an occupant positioned upon a vehicle seat, an occupantpositioned within a wheelchair, or an occupant within a neonatalincubator, may be subject to motion in up to six directions of freedom,including rotation and translation about each of a roll, pitch, and yawaxis. Due to uneven earth surfaces, the payload often experiencesdisturbances in travel when a vehicle attached to the platformencounters obstructions. In particular, disturbances as a result ofsurface condition can be especially dramatic when the platform includesa rigid or stiff suspension system, such as those typically found intractors and other heavy machinery.

SUMMARY

In accordance with aspects of the present disclosure, there are providedsystems and methods for actively isolating a payload from a disturbance.For example, there are provided a vehicle seat, a seat system for avehicle, and methods for controlling movement of a vehicle seat aboutone or more axes, such as a roll or a pitch axis, based on at least ameasured lateral acceleration of a pivot point about which the seatmoves. In one example, a seat system includes a seat configured to moveat a command angle, and a controller configured to generate a commandsignal to instruct an actuator coupled to the seat to adjust the commandangle to compensate for movement of the vehicle. Accordingly, variousimplementations provide systems and methods for actively isolating apayload, such as an occupant of a vehicle seat, from movement anddisruptive forces. In such implementations, the payload is maintained ata static position despite movement or rotation of the vehicle.

In particular, several aspects of the present disclosure address theundesired effects on the command signal of lateral accelerations causedby steering (i.e., cornering accelerations) the vehicle. Severalimplementations generate the command signal responsive to receiving arotation of the vehicle and a lateral acceleration of the pivot point.The lateral acceleration of the pivot point is corrected by removing anylateral acceleration caused by steering the vehicle. Such aspects andimplementations provide a more natural, isolated, and disturbance-freetravel experience for the payload. While various aspects andimplementations are described herein with reference to a vehicle seat ora vehicle seat system, further aspects and implementations may includeother platforms systems for supporting a payload sensitive todisturbance, such as wheelchairs, gurneys, beds, neonatal incubators,and heavy machinery.

According to one aspect, provided is a seat system for a vehicle. Theseat system may include a seat, a support structure coupled to the seatthat allows the seat to move about a first axis of a pivot, a firstsensor positioned to detect movement of the vehicle, a second sensorpositioned to detect lateral acceleration of the pivot, an actuatorconfigured to move the seat, and a controller configured to receive afirst signal from the first sensor and a second signal from the secondsensor, generate a command signal based at least in part on the firstsignal and the second signal to instruct the actuator to position theseat at a desired command angle, wherein the controller is configured tocorrect the command signal for lateral accelerations caused by steeringthe vehicle, and provide a force command to the actuator to move theseat at the desired command angle based on at least the command signal.

In one example, the first signal includes at least a roll rate of thevehicle about a second axis, and the second signal includes a lateralacceleration of the pivot in a direction substantially perpendicular toa direction of travel of the vehicle. According to an example, the seatsystem may further include a third sensor positioned to detect a yawrate of the vehicle, and the controller may be configured to generatethe command signal according to:

${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$whereinθ₁ is a rotation of the vehicle about the second axis, {umlaut over (x)}is the lateral acceleration of the pivot, speed is a speed of thevehicle, yaw rate is the yaw rate of the vehicle, and L₂ is a distancebetween the first axis and a substantially center virtual point of thepayload. In a further example, the seat system may further include aglobal positioning system (GPS) configured to calculate the speed of thevehicle. In one example, the second sensor is positioned at the pivot.

According to one example, the controller is further configured todetermine a frequency of the first signal and generate the commandsignal based on at least the first signal and the second signal andcorrect the command signal for lateral accelerations caused by steeringthe vehicle if the frequency of the first signal is greater than orequal to a reference threshold, and generate the command signal based onthe first signal when the frequency of the first signal is less than thereference threshold. In a further example, the reference thresholdincludes a frequency between about 0.1 Hz and about 1.0 Hz. In oneexample, the seat system may further include a third sensor positionedto detect a yaw rate of the vehicle, and the controller may beconfigured to generate the command signal according to:

${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$whereinθ₁ is a rotation of the vehicle about the second axis, {umlaut over (x)}is the lateral acceleration of the pivot, speed is a speed of thevehicle, yaw rate is the yaw rate of the vehicle, and L₂ is a distancebetween the first axis and a substantially center virtual point of thepayload, when the frequency of the first signal is greater than or equalto the reference threshold. In a further example, the controller isconfigured to generate the command signal according to:

${\theta_{1} + {\left( \frac{L_{1}}{L_{2}} \right)\theta_{1}}},$whereinθ₁ is the rotation of the vehicle about the second axis, L₂ is thedistance between the first axis and the substantially center virtualpoint of the payload, and L₁ is a distance between the second axis andthe first axis, when the frequency of the first signal is less than thereference threshold.

According to one example, the second axis is substantially parallel to adirection of travel of the vehicle, and the actuator is furtherconfigured to rotate the seat in substantially an opposite directionfrom a rotation of the vehicle.

Another aspect is directed to a method of controlling seat movement in avehicle. In one example, the method may include receiving a first signalfrom a first sensor positioned to detect movement of the vehicle,receiving a second signal from a second sensor positioned to detectlateral acceleration of a pivot including a first axis about which asupport structure coupled to a seat allows movement of the seat,generating a command signal based at least in part on the first signaland the second signal to instruct an actuator to position the seat at adesired command angle, wherein generating the command signal includescorrecting the command signal for lateral accelerations caused bysteering the vehicle, and providing a force command to the actuator tomove the seat at the desired command angle based on at least the commandsignal.

In one example, the first signal includes at least a roll rate of thevehicle about a second axis, and the second signal includes a lateralacceleration of the pivot in a direction substantially perpendicular toa direction of travel of the vehicle. In a further example, the methodmay further include receiving a third signal from a third sensorpositioned to detect a yaw rate of the vehicle, and generating thecommand signal may include generating the command signal according to:

${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$whereinθ₁ is a rotation of the vehicle about the second axis, {umlaut over (x)}is the lateral acceleration of the pivot, speed is a speed of thevehicle, yaw rate is the yaw rate of the vehicle, and L₂ is a distancebetween the first axis and a substantially center virtual point of thepayload. According to one example, the method may further includereceiving the speed of the vehicle from a global positioning system(GPS).

According to one example, the method may further include determining afrequency of the first signal, and generating the command signal basedon at least the first signal and the second signal may includegenerating the command signal based on at least the first signal and thesecond signal when a frequency of the first signal is greater than orequal to a reference threshold, and the method further comprisesgenerating the command signal based on the first signal when thefrequency of the first signal is less than the reference threshold. In afurther example, the reference includes a frequency between about 0.1 Hzand about 1.0 Hz.

In one example, the method may further include receiving a third signalfrom a third sensor positioned to detect a yaw rate of the vehicle, andgenerating the command signal based on at least the first signal and thesecond signal when the frequency of the first signal is greater than orequal to the reference threshold may include generating the commandsignal according to:

${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$whereinθ₁ is a rotation of the vehicle about the second axis, {umlaut over (x)}is the lateral acceleration of the pivot, speed is a speed of thevehicle, yaw rate is the yaw rate of the vehicle, and L₂ is a distancebetween the first axis and a substantially center virtual point of thepayload. In one example, generating the command signal based on thefirst signal when the frequency of the first signal is less than thereference threshold includes generating the command signal according to:

${\theta_{1} + {\left( \frac{L_{1}}{L_{2}} \right)\theta_{1}}},$whereinθ₁ is the rotation of the vehicle about the second axis, L₂ is thedistance between the first axis and the substantially center virtualpoint of the payload, and L₁ is a distance between the second axis andthe first axis.

Another aspect is directed to a vehicle seat. In one example, thevehicle seat may include a seat configured to move at a command angleabout a first axis of a pivot relative to a substantially horizontalorientation, and a controller configured to receive a first signal ofdetected movement of a vehicle and a second signal of detected lateralacceleration of the pivot, and generate a command signal based on atleast the first signal and the second signal to instruct an actuator toposition the seat at a desired command angle, wherein the controller isconfigured to correct the command signal for lateral accelerationscaused by steering the vehicle.

In one example, the controller is further configured to provide a forcecommand to move the seat at the desired command angle based on at leastthe command signal. According to one example, the first signal includesat least a roll rate of the vehicle about a second axis, and the secondsignal includes a lateral acceleration of the pivot in a directionsubstantially perpendicular to a direction of travel of the vehicle. Inone example, the controller is further configured to receive a detectedyaw rate of the vehicle, and the controller is configured to generatethe command signal according to:

${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$whereinθ₁ is a rotation of the vehicle about the second axis, {umlaut over (x)}is the lateral acceleration of the pivot, speed is a speed of thevehicle, yaw rate is the yaw rate of the vehicle, and L₂ is a distancebetween the first axis and a substantially center virtual point of thepayload.

According to one example, the controller is further configured todetermine a frequency of the first signal and generate the commandsignal based on at least the first signal and the second signal andcorrect the command signal for lateral accelerations caused by steeringthe vehicle if the frequency of the first signal is greater than orequal to a reference threshold, and generate the command signal based onthe first signal when the frequency of the first signal is less than thereference threshold. In a further example, the reference thresholdincludes a frequency between about 0.1 Hz and about 1.0 Hz.

In one example, the controller is further configured to receive adetected yaw rate of the vehicle, and the controller is configured togenerate the command signal according to:

${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$whereinθ₁ is a rotation of the vehicle about the second axis, {umlaut over (x)}is the lateral acceleration of the pivot, speed is a speed of thevehicle, yaw rate is the yaw rate of the vehicle, and L₂ is a distancebetween the first axis and a substantially center virtual point of thepayload, when the frequency of the first signal is greater than or equalto the reference threshold. According to one example, the controller isconfigured to generate the command signal according to:

${\theta_{1} + {\left( \frac{L_{1}}{L_{2}} \right)\theta_{1}}},$whereinθ₁ is the rotation of the vehicle about the second axis, L₂ is thedistance between the first axis and the substantially center virtualpoint of the payload, and L₁ is a distance between the second axis andthe first axis, when the frequency of the first signal is less than thereference threshold.

Still other aspects, examples, and advantages of these exemplary aspectsare discussed in detail below. Further implementations may include meansfor performing any of the processes recited herein. Moreover, it is tobe understood that both the foregoing information and the followingdetailed description are merely illustrative examples of variousaspects, and are intended to provide an overview or framework forunderstanding the nature and character of the claimed subject matter.Any example disclosed herein may be combined with any other example.References to “an example,” “some examples,” “an alternate example,”“various examples,” “one example,” “at least one example,” “this andother examples” or the like are not necessarily mutually exclusive andare intended to indicate that a particular feature, structure, orcharacteristic described in connection with the example may be includedin at least one example. The appearances of such terms herein are notnecessarily all referring to the same example.

Furthermore, in the event of inconsistent usages of terms between thisdocument and documents incorporated herein by reference, the term usagein the incorporated references is supplementary to that of thisdocument; the term usage in this document controls. In addition, theaccompanying drawings are included to provide illustration and a furtherunderstanding of the various aspects and examples, and are incorporatedin and constitute a part of this specification. The drawings, togetherwith the remainder of the specification, serve to explain principles andoperations of the described and claimed aspects and examples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration of a vehicle;

FIG. 1B is an illustration of the vehicle of FIG. 1A experiencing a rollevent;

FIG. 2 is an illustration of an example vehicle seat and vehicle seatsystem according to various aspects discussed herein;

FIG. 3 is a further illustration of an example vehicle seat and vehicleseat system according to various aspects discussed herein;

FIG. 4 is an illustration of a flow diagram for controlling vehicle seatmovement according to various aspects discussed herein;

FIG. 5 is an illustration of a block diagram for controlling vehicleseat movement according to various aspects discussed herein;

FIG. 6 is an illustration of a controller that may be used with variousaspects discussed herein; and

FIG. 7 is an example illustration of a coordinate system for a vehicleaccording to various aspects discussed herein.

DETAILED DESCRIPTION

Aspects and implementations disclosed herein are not limited to thedetails of construction and the arrangement of components set forth inthe following description or illustrated in the drawings. Aspects andimplementations disclosed herein are capable of being practiced or ofbeing carried out in various ways.

In accordance with aspects of the present disclosure, there are providedsystems and methods for actively isolating a payload supported by aplatform from a disturbance. In at least one example, this may include avehicle seat, a seat system for a vehicle, and methods for controllingmotion of a vehicle seat to isolate an occupant from movement of thevehicle. In particular, various aspects and implementations maintain apayload at a static position despite movement or rotation of thevehicle. In one example, a seat system includes a seat configured tomove at a command angle, and a controller configured to generate acommand signal to instruct an actuator coupled to the seat to adjust thecommand angle to compensate for movement of the vehicle. In contrast toprevious attempts of controlling seat movement that rely on one or moregeometric assumptions about motion characteristics of the vehicle,various aspects and implementations generate a command signal based atleast in part on a lateral acceleration of a pivot about which the seatrotates. Generating command signal based at least in part on the lateralacceleration of the pivot, and in various examples, the rotation of thevehicle, enables a significant improvement in performance due toimproved accuracy in tracking vehicle motion.

Further examples further improve the performance of previous payloadactive isolation systems and methods by correcting the influence oflateral accelerations caused by steering the vehicle (i.e., turningaccelerations), on the command signal. Without correction, in somesituations turning accelerations may cause the command signal to becomeinappropriately, and/or dangerously, large during normal drivingconditions. Accordingly, various aspects and implementations determineand correct the command signal for lateral accelerations caused bysteering. Such aspects and implementations provide a more natural,isolated, and disturbance-free travel experience for the payload. Whilevarious aspects and implementations are described herein with referenceto a vehicle seat or vehicle seat system, further aspects andimplementations may include other systems and apparatuses for supportinga payload sensitive to disturbance.

Several examples discussed herein include a vehicle seat and a seatsystem for a vehicle. FIGS. 1A and 1B illustrate an example seat andseat system for a vehicle according to several implementations. Inparticular, FIG. 1A shows a vehicle 102 in the form of a tractortraveling on a substantially level surface, and FIG. 1B shows thetractor 102 encountering a roll event at a vehicle roll angle of θ₁. Itis appreciated that portions of the tractor 102 shown in FIGS. 1A and 1Bhave been omitted to facilitate description of various implementations.Various references are made herein to a pitch, roll, and yaw axis of avehicle. Turning briefly to FIG. 7, an example illustration of acoordinate system showing a roll, a pitch, and a yaw axis of a vehicle702 according to various aspects and implementations is shown. Whentraveling in a straight line, the vehicle 702 travels in the directionof travel indicated by line 704 and along a roll axis (x-axis).Extending perpendicular to the roll axis is the pitch axis (y-axis),about which the vehicle 702 may pitch when the front tires 706, or reartires 708, encounter an obstacle. The yaw axis (z-axis) extendsorthogonal to the roll axis and pitch axis. The vehicle rotates aboutthe yaw axis when the vehicle 702 is steered, as shown in FIG. 7.Rotation is represented by ghost line 710.

Returning to FIGS. 1A and 1B, a payload (e.g., person 104) is shownsupported in the seat 106 in a substantially vertical orientation alongan imaginary reference vertical centerline 108 which passes through thebody of the person 104 who is sitting in the seat 106. In this example,the vertical centerline 108 bisects the person 104 and the seat 106 whenboth the seat 106 and the vehicle 102 are in a nominal, substantiallylevel horizontal orientation as shown in FIG. 1A. This is because theseat 106 is substantially symmetrical as viewed in FIG. 1A. In othertypes of vehicles, the seat 106 may be located to the left or right ofthe vertical centerline 108.

The seat 106 may be secured to the floor 110 of the vehicle via asupport structure 112. The support structure 112 includes a pivot 128which permits the seat 106 to move or rotate relative to thesubstantially horizontal orientation about a first axis 114 which issubstantially parallel to a direction in which the vehicle 102 is movingwhen the vehicle 102 is moving in a straight line. FIGS. 1A and 1B showthe axis 114 located at a distance below the seat 106, and in variousimplementations the axis 114 may be located higher or lower than shown.The axis 114 is fixed relative to the vehicle 102. In variousimplementations the vehicle 102 may roll about a second axis 116 whichis substantially parallel with the axis 114 and the direction in whichthe vehicle 102 is moving.

As shown in FIGS. 1A and 1B, a distance L₁ represents the length betweenthe first axis 114 and the second axis 116. A second distance, L₂,represents the length between the first axis 114 and a substantiallycenter virtual point of the payload (e.g., a center of a head 118 of theoccupant 104 of the vehicle 102). In various implementations, the topend of L₂ will reside at or above a position associated with the head ofa person sitting in the seat, and for example, may be in a range of 3-5feet.

In FIG. 1B, the left tires 120 of the vehicle 102 have hit anobstruction 122 in the surface over which the vehicle 102 is traveling,causing the vehicle 102 to rotate counter-clockwise (when viewed fromthe front). Rotation of the vehicle 102 about the second axis 116 is anapproximation for the rotation of the vehicle 102 about the bottom ofthe right tires and is used for symmetry. The vehicle 102 hasapproximately rotated by the angle θ₁, which represents the anglebetween the vertical centerline 108 and a vehicle centerline 124. If theseat 102 is not positioned at the center of the vehicle 102 (i.e.,positioned to one or the other side of the center), then θ₁ isdetermined by the rotation of the vehicle centerline 124 from thenominal position in FIG. 1A to a rotated position (e.g., in FIG. 1B). Inseveral implementations, when the vehicle 102 rotates counter-clockwisethe seat 106 is rotated about the axis 114 clockwise (opposite thedirection of roll of the vehicle 102). The seat 106 may be rotated by anactuator coupled to the support structure 112. Similarly, when thevehicle 102 rotates clockwise the seat 106 is rotated about the axis 114counter-clockwise. In both implementations, a controller incommunication with at least the actuator provides a force command tocause the actuator to rotate the seat by the angle θ₂, which is theangle between the vehicle centerline 124 and a seat centerline 126(i.e., an angle from a nominal substantially horizontal position).

In various implementations, θ₂ may be generated based at least in parton a first signal of detected movement of the vehicle 102, and a secondsignal of detected lateral acceleration of the pivot 128. For instance,in one example the angle θ₂ is determined by the controller accordingto:

${\theta_{2} = {\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}}},$in which, θ₁ is the rotation of the vehicle 102 about the second axis116 (i.e., the vehicle roll angle), {umlaut over (x)} is a lateralacceleration of the pivot 128, speed is a speed of the vehicle 102, yawrate is a yaw rate of the vehicle 102, and L₂ is the distance betweenthe first axis 114 and a substantially center virtual point 130 of thepayload. In further examples, the controller is configured to determinewhether a frequency of the first signal exceeds a threshold, beforegenerating the control signal. In such an implementation, the controllerdetects a frequency of the first signal and compares it to thethreshold. If the threshold is exceeded (i.e., the frequency of thefirst signal is greater than the threshold), or the frequency is equalto the threshold, the controller generates the command signal based onthe first signal of detected rotation of the vehicle 102 and the secondsignal of detected lateral acceleration of the pivot 128, as describedabove. If the threshold is not exceeded (i.e., the frequency of thefirst signal is less than threshold), the angle θ₂ is determined by thecontroller according to:

${\theta_{1} + {\left( \frac{L_{1}}{L_{2}} \right)\theta_{1}}},$in which, θ₁ is the rotation of the vehicle about the second axis 116,L₂ is the distance between the pivot 128 and the substantially centervirtual point of the payload, and L₁ is a distance between the firstaxis 114 and the second axis 116. Such an implementation maintains thepayload at a static position despite disturbances of variable amplitude.

In various implementations, locating the axis 114 close to the floor 110is preferable because θ₂ may increase when L₁ increases relative to L₂.Accordingly, larger rotations may be required to compensate for a fixedamount of roll if the height of the axis 114 is increased from the floor110. As a result, the person 104 is rotated about a position tosubstantially reduce or minimize side-to side and/or front/backmovement. In various implementations, the head 118 of the occupantremains substantially on the original vertical centerline 108 at astatic position despite movement of the vehicle 102.

Turning now to FIG. 2 with continuing reference to FIGS. 1A-1B, shown isone example of a vehicle seat system including a vehicle seat, such asvehicle seat 106 shown in FIGS. 1A and 1B. The seat 106 is shown with abottom 204 and a seat back 206 which is connected to the bottom 204. Apair of arms 208 extends forward from the seat back 206. An advantage ofthis seat system is that any impact of the arms 208 against a torso ofthe person 104 due to side-to-side rocking of the vehicle 102 will besubstantially reduced (or minimized). A similar improvement will occuron the seat back 206 whereby the lateral translation of the seat back206 relative to a person's back will also be substantially reduced. Alinear actuator 210 is pivotally connected to the support structure 112(at a location 212) and can interact with the seat 106 to cause the seat106 to rotate about the axis 114. In this example, the linear actuator210 is also pivotally connected to the floor 110 of the vehicle at alocation 214. The linear actuator 210 is extended or retracted in thedirection of a two-headed arrow 216 to cause the seat 106 to rotateabout the axis 114 in the direction of a two-headed arrow 218. Thelinear actuator 210 can be, for example, an electromagnetic linearmotor, a hydraulic cylinder, or a pneumatic cylinder. The linearactuator 210 instead can be some other type of actuator such as a rotaryactuator (electromagnetic, hydraulic, or pneumatically powered) that iscoupled between the seat 106 and the floor 110. Any type of actuator canbe directly coupled to the seat 106 or it may act through some type ofgear train, linkages or other transmission mechanism. The actuator 210can be connected to a different portion of the support structure 112, orseat 106, and a different portion of the vehicle 102 (other than thefloor 110, e.g. a wall of the driver compartment). Control of theactuator 210 is discussed below with reference to at least FIGS. 3-7.

The seat 106 is shown with only a single degree of freedom about theaxis 114 (a roll axis) relative to the vehicle 102. This single degreeof freedom could instead be about a pitch axis, a yaw axis, or about aplurality of axes (i.e., roll, pitch, and/or yaw). In this case, theaxis 114 is oriented front-to-back as viewed in FIG. 1A and allows theseat 106 to be controlled for side to side rolling. In another example,the seat 106 may be outfitted with one or more additional actuators (notshown) to provide movement of the seat 106 in one or more additionaldegrees of freedom. For example, instead of mounting the intermediatesupport structure 112 to the floor 110, the intermediate supportstructure 112 can be mounted to a platform (not shown) which is moved upand down in the vertical direction by an additional actuator to reducethe vertical vibrations felt by the driver as the vehicle travels over aroad (or this vertical actuator can be interposed between the structureand the seat). An example of this type of vertical active suspensionsystem is shown in U.S. Pat. No. 8,095,268, titled “ACTIVE SUSPENDING”,which is incorporated herein by reference in its entirety. The verticalactive suspension system can be operated independently of the rotatingseat 106. The L₂ distance (FIGS. 1A and 1B) will vary with the motionsassociated with a vertical isolation mechanism. This effect can beincluded in the processor calculations based on inputs from a sensorwhich detects a distance between the platform and the floor. Inaddition, the vertical isolation system can be used to offset anypotential raising or lowering of the head of the person due to thecombined rotation of the vehicle (e.g., relative to the ground), androtation of the seat relative to the vehicle. Further configurations fora vehicle seat and vehicle seat system may include those described inU.S. Pub. No. 2014/0316661, titled “SEAT SYSTEM FOR A VEHICLE,” which ishereby incorporated by reference herein in its entirety.

Turning to FIG. 3, operation of the actuator 210 is controlled by acontroller 302. A first sensor 304 can measure an aspect of motion,which in this example is a roll rate of the vehicle. The controller 302may receive a signal (i.e., input) from the first sensor 304 in the formof roll rate data via a bus 310. The controller 302 calculates theintegral of the roll rate data to determine an instantaneous vehicleroll angle θ₁ (FIG. 1B). In various other examples, the input from thefirst sensor includes a component of a vehicle roll rate, and thecontroller is configured to calculate the vehicle roll rate based on atleast the component of the vehicle roll rate. A second sensor 312 canmeasure a second aspect of motion, which in this example is a lateralacceleration of the pivot 128. In one example, the second sensor 312 isan accelerometer positioned on the pivot 128 at substantially the sameheight (or location) as the axis 114. However, in various other examplesthe accelerometer may be positioned on the vehicle 102, the supportstructure 112, or the seat 106. The controller 302 may receive a secondsignal (i.e., second input) from the second sensor 312 in the form of alateral acceleration of the pivot 128 via a bus 318. In various otherexamples, the second input includes a second component of a lateralacceleration of the pivot 128, and the controller 302 may be configuredto calculate the lateral acceleration of the pivot 128 based on at leastthe second component. The controller 302 may then use θ₁ and the lateralacceleration of the pivot 128 to generate a command signal including theinstantaneous command angle θ₂ (FIG. 1B), and correct the command signalfor lateral accelerations caused by steering the vehicle. In furtherexamples, such as when a frequency of the signal from the first sensor304 is below a determined threshold, the controller may use θ₁ alongwith L₂ and L₁, to generate a command signal including the instantaneouscommand angle θ₂ (FIG. 1B).

In one example, the command signal is corrected based on a yaw ratemeasured by a third sensor 314 and a detected speed of the vehicle 102.In various implementations, the third sensor 314 may be positioned onthe vehicle 102, the seat 106, or the support structure 112, as shown inFIG. 3. The third sensor 314 may include any yaw rate sensor, such asany gyroscopic device that measures the vehicle's angular velocityaround its vertical axis. In further implementations, the third sensor314 may include a steering wheel sensor positioned to determine the yawrate of the vehicle 102 based on movement of a steering wheel. Thecontroller 302 receives the yaw rate via a bus 316. The vehicle speedmay be measured by one or more speed sensors (not shown) positioned tomeasure the rate at which the vehicle 102 is traveling. For instances,the speed sensor may be positioned near a gear of a transmission of thevehicle 102 to measure a speed relative to the rotation of the gear.Other appropriate methods for measuring the speed of the vehicle may beemployed by further implementations and are within the scope of thisdisclosure. For instance, the speed sensor may include a globalpositioning system (GPS) adapted to determine a speed of the vehicle. Inone example, the GPS uses time and location data to determine the speedof the vehicle 102 based on how much distance is covered within a giventime frame. The measured speed of the vehicle is received by thecontroller 302 via a bus. The controller 302 may then subtract theproduct of the yaw rate and speed from the lateral acceleration of thepivot to remove any effects caused by steering the vehicle 102. Furtherexamples for correcting the command signal for turning accelerations aredescribed below with reference to FIGS. 4 and 5.

Next, the controller 302 uses a look-up table to determine the desiredactuator position in order to achieve the calculated θ₂. The actuatorposition look-up table may include any array that replaces a runtimecomputation with an indexing operation. For example, the actuatorposition look-up table may include an array of pre-calculated andindexed actuator positions stored in static program storage. Note thatthe controller 302 receives position data from the actuator 210 via abus 306. The position data is indicative of a position of the actuator210 which is correlated to a position of the seat 106 about the axis114. As such, the controller 302 is informed of the current position(e.g., displacement) of the actuator 210 when generating the commandsignal. In various other examples, the controller may perform one ormore runtime computations to determine the actuator position necessaryto achieve the desired seat position. It should be noted various controllaws such as PI, PID, or other known control laws, can be used in theimplementations described herein.

The controller 302 then issues a force command to the actuator 210 via abus 308 which causes the actuator 210 to move the seat to the desiredposition. By successively repeating these steps, the controller 302utilizes input from the first sensor 304, the second sensor 312, and infurther examples the third sensor 314, to determine a desired motion ofthe seat 106 about the axis 114, and then operates the actuator 210 tocause the desired motion of the seat 106 about that axis. This resultsin a reduction (or minimizing) of the acceleration of a payload (e.g.,person's head) positioned in the seat 106 in a substantially horizontaldirection. Preferably the controller 302 controls motion of the seat 106in order to reduce displacement of the virtual center point 130 alongthe reference vertical centerline 108 as the vehicle 102 is rotated(e.g., about the axis 116 in FIG. 1B). This example is advantageous inthat it (a) is substantially insensitive to lateral accelerations causedby turning (when the vehicle makes a left or right turn), and (b)requires minimal motion sensors. This arrangement assumes that there isa stationary roll center height (i.e., L₁ does not vary).

If it is desired to calculate L₁ continuously in real time as thevehicle 102 is moving, the controller 302 may calculate L₁ using theequation L₁=lateral velocity/roll rate where the lateral velocity iscalculated by integrating the lateral acceleration signal. It should benoted that preferably gravity correction is done on the output of anylateral accelerometers described in this application. This means thatthe component of gravity coupled into the lateral accelerometer as thevehicle 102 and/or seat 106 rotates is taken into consideration.

Various aspects and implementations discussed herein control movement ofa platform to maintain a payload supported by the platform at asubstantially static position, despite movement of a vehicle attached tothe platform. At least one method for controlling movement of a platformis discussed below with reference to FIG. 4. In various examples, themethod includes controlling movement of a vehicle seat during rotationof a vehicle. FIG. 4 is discussed with continuing reference to thevehicle seat and vehicle seat systems described above with reference toFIGS. 1-3. In various examples, such a method may include receiving afirst signal, receiving a second signal, generating a command signal,and providing a force command. In further examples, the method mayinclude receiving a third signal and determining a frequency of thefirst signal.

In act 402, the method may include receiving a first signal from a firstsensor positioned to detect movement of the vehicle. In variousexamples, the first signal includes at least a roll rate of the vehicleabout a second axis, such as the axis 116 shown in FIG. 1. The secondaxis may include an axis extending parallel to a direction of travel ofthe vehicle, as described above. The first signal is received by acontroller via one or more data bus. Similarly, in act 404 the methodmay include receiving a second signal from a second sensor. In variousexamples, the second sensor is positioned to detect a lateralacceleration of a pivot having a first axis about which a supportstructure coupled to the seat allows movement of the seat. The seat maybe rotated by an actuator, as discussed above, at a command anglerelative to a substantially horizontal orientation.

In various examples, receiving the second signal includes receiving alateral acceleration of the pivot in a direction substantiallyperpendicular to a direction of travel of the vehicle. For instance,this may include a total lateral acceleration of the vehicle duringmovement of the vehicle. The second signal is received by the controllervia a second bus. In further examples, the method 400 may additionallyinclude receiving a third signal from a third sensor positioned todetect a yaw rate of the vehicle (act 406). As described above, the yawrate includes an angular acceleration about a vertical axis extendingthrough the vehicle. A controller may receive the yaw rate from thethird sensor via one or more bus. While not shown in FIG. 4, in furtherexamples, the method may also include receiving additional signals fromone or more additional sensors. For instance, in one implementation thecontroller receives a detected speed of the vehicle from a speed sensor.The speed sensor may be positioned proximate a gear of a transmission ofthe vehicle, or include a global positioning system (GPS), configured todetect and measure the rate at which the vehicle is traveling. Similarto the first signal, second signal, and/or yaw rate, the one or moreadditional signals may be received at the controller via a bus.

Turning to act 410, in various examples the method 400 includesgenerating a command signal based at least in part on the first signaland the second signal to instruct an actuator to position the seat at adesired command angle to maintain a payload at a static position duringmovement of the vehicle. In several implementations, this includescorrecting the command signal for lateral accelerations caused bysteering the vehicle. While using the lateral acceleration to generate acommand signal offers significant improvements in performance over knowncontrol methods, such an approach is susceptible to inappropriateresponses as a result of cornering accelerations. Accordingly, variousaspects and implementations correct for such effects by removingcornering accelerations caused by steering the vehicle.

According to one example, the act of generating a command signalincludes generating the command signal based at least in part on arotation of the vehicle and a lateral acceleration of the pivot. Thecommand signal may be used by the controller to instruct an actuatorcoupled to the seat to rotate the seat about the pivot at a commandangle θ₂. As described above, often this includes rotating the seat insubstantially an opposite direction from the rotation of the vehicle. Infurther examples, this includes generating the command signal based onthe rotation of the vehicle, the lateral acceleration of the pivot, ayaw rate of the vehicle, a speed of the vehicle, and a distance betweenan axis about which the seat rotates and a substantially center virtualpoint of the payload. Such a process corrects the command signal foradverse effects as a result of accelerations from steering the vehiclearound a corner. In particular, various examples include generating thecommand signal according to:

${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$in which, θ₁ is the rotation of the vehicle about the second axis,{umlaut over (x)} is the lateral acceleration of the pivot, speed is thespeed of the vehicle, yaw rate is the yaw rate of the vehicle, and L₂ isthe distance between the first axis and the substantially center virtualpoint of the payload. In such an implementation, the distance L₂ isdetermined by measuring the distance from the first axis, about whichthe support structure coupled to the seat allows movement of the seat,to the center of the payload of interest. For instance, this may includethe center of the head of an average height person sitting in the seat.

In act 412, the method 400 provides one or more force commands to theactuator to move the seat at the desired command angle based on at leastthe command signal. For example, the controller may use a look-up tableto determine the desired actuator position to achieve the calculated θ₂.The actuator position look-up table may include any array that replacesa runtime computation with an indexing operation, as described abovewith reference to FIG. 3. For example, the actuator position look-uptable may include an array of pre-calculated and indexed actuatorpositions stored in static program storage. In other examples, thecontroller may perform one or more runtime computations to determine thedesired actuator position in order to achieve the calculated θ₂.

As discussed above, the actuator can induce roll (and/or pitch) into thevehicle seat, or a support structure attached to the vehicle seat, toisolate the payload from vehicle movement. The force command causes theactuator to rotate the seat by the angle θ₂. In particular, electricalenergy generated by the controller is delivered to the actuator causingthe actuator to extend or retract to a predetermined position specifiedby the command signal, causing the seat to rotate. As discussed above,the linear actuator can be, for example, an electromagnetic linearmotor, a hydraulic cylinder, or a pneumatic cylinder. The linearactuator instead may also be some other type of actuator such as arotary actuator (electromagnetic, hydraulic, or pneumatically powered)that is coupled between the seat and the floor of the vehicle.

In act 408, according to one example the method 400 includes determininga frequency of the first signal (i.e., the rotation of the vehicle). Invarious examples, this may include separating the signal into componentsabove and below a frequency threshold using a linear frequency dependentfilter. In various examples, the controller is configured to generatethe command signal based on different algorithms depending on therelationship between the detected frequency and the threshold value. Thethreshold value, for instance, may include a user defined, or adynamically created, threshold frequency. In at least one example, thethreshold includes a frequency between about 0.1 Hz and about 1.0 Hz. Ifcomponents of the detected frequency exceeds (i.e., is greater than), orequal to, the threshold, the controller may generate the command signalbased on a first algorithm, and if components of the detected frequencyis less than the threshold, the controller may generate the commandsignal based on a second algorithm, the second algorithm being differentfrom the first algorithm.

In one example, responsive to comparing the detected frequency to thethreshold and determining that the detected frequency exceeds thethreshold, or is equal to the threshold, the method 400 includesgenerating the command signal according to:

${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$as described above. However, if responsive to comparing the detectedfrequency to the threshold the controller determines that the detectedfrequency is less than the threshold, the method 400 may includegenerating the command signal according to:

${\theta_{1} + {\left( \frac{L_{1}}{L_{2}} \right)\theta_{1}}},$in which, θ₁ is the rotation of the vehicle about the second axis, L₂ isthe distance between the first axis and the substantially center virtualpoint of the payload, and L₁ is a distance between the second axis andthe first axis. L₁ and L₂ may be determined as described above.Accordingly, various aspects and implementations permit stabilization ofthe payload when an amplitude of the disturbance is large or small,causing the vehicle to rotate severely or minimally. Suchimplementations provide an improved active stabilization system.

Turning now to FIG. 5, shown is an illustration of a block diagram forcontrolling vehicle seat movement according to various aspects discussedherein. Processes described with reference to FIG. 5 may be performed byone or more controllers, such as the controller 302 described withreference to FIG. 3, or the controller 600 further described below withreference to FIG. 6. The controller may use any appropriate control lawsuch as PI, PID, or other known control laws to implement the variousprocesses. FIG. 5 is described with reference to FIGS. 1-4.

As discussed above with reference to FIGS. 1-4, the controller mayreceive a first input, a second input, and in further examples,additional inputs, from a first sensor, a second sensor, and one or moreadditional sensors. In various examples the first sensor is positionedto detect movement of the vehicle, the second sensor is positioned todetermine a lateral acceleration of a pivot attached to the seat, athird sensor is positioned to determine a yaw rate of the vehicle, and aspeed sensor is positioned to determine a speed of the vehicle.Accordingly, FIG. 5 shows the controller as receiving a vehicle rollrate, a yaw rate, a speed, and a lateral acceleration as a plurality ofinputs. In one example, the controller may also receive as an input L₂,a distance between a substantially center virtual point of the payloadand an axis of the pivot. In various other examples, the controller isconfigured to determine the distance L₂.

At block 502, the controller is configured to receive the signal fromthe first sensor 304 in the form of roll rate data via a bus. Thecontroller calculates the integral of the roll rate data to determine aninstantaneous vehicle roll angle θ₁. In various examples, the vehicleroll angle includes the angle of rotation of the vehicle between avertical centerline (e.g., vertical centerline 108 of FIG. 1) and avehicle centerline (e.g., vehicle center 124 of FIG. 1).

At block 504, the controller is configured to receive the yaw rate, thespeed, the lateral acceleration of the pivot point, and the distance L₂.Each input may be received by the controller via one or more bus. Ingenerating the command signal, the controller is configured to correctthe command signal for cornering accelerations that result from steeringthe vehicle. Often such forces have an undesirable effect on the commandsignal, such as inappropriately increasing or decreasing the commandangle. Accordingly, at block 504 the controller may be configured toexecute one or more algorithms to remove the effects of corneringacceleration from the lateral acceleration of the pivot point. In oneexample, this includes executing:

$\frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}},$in which, {umlaut over (x)} is the lateral acceleration of the pivot,speed is the speed of the vehicle, yaw rate is the yaw rate of thevehicle, and L₂ is the distance between the first axis and thesubstantially center virtual point of the payload. While in one examplethe controller may be configured to correct the command signal for theacceleration effects causing by steering the vehicle based on a vehiclespeed and yaw rate, in various further examples the lateral accelerationcaused by steering may be estimated based on other suitablecalculations. For instance, in one example the controller may beconfigured to estimate and remove the lateral acceleration caused bysteering from the lateral acceleration of the pivot based on a(speed)*(steering angle) calculation. For instance, the controller maysubtract (speed)*(steering angle) from the lateral acceleration of thepivot. Steering angle may include the angle at which the vehicle issteered when traveling through a corner, and may be measured by aposition sensor configured to detect movement of a steering wheel. Inother examples, the lateral acceleration caused by steering may beestimated based on an estimated turning radius of the vehicle whentraveling through the corner. Such information may be received from aGPS system and similarly removed from the lateral acceleration of thepivot. At block 506 the controller is configured to combine the resultand the vehicle roll angle, having previously corrected for corneringaccelerations. In various examples this includes adding the vehicle rollangle and the corrected lateral acceleration of the pivot.

At block 508, the controller provides one or more force commands to theactuator to move the seat at the desired command angle based on at leastthe command signal. For example, the controller may use a look-up tableto determine the desired actuator position to achieve the calculated θ₂,or perform one or more runtime computations to determine the desiredactuator position. Such processes are further described above withreference to FIGS. 1-5.

Referring to FIG. 6, there is illustrated a block diagram of acontroller 600, in which various aspects and functions are practiced.FIG. 6 is described with reference to the several aspects andimplementations discussed above with reference to FIGS. 1-5. Forexample, the controller 600 may include the controller 302 shown in FIG.3. As shown, the controller 600 can include one or more systemcomponents that exchange information. More specifically, the controller600 can include at least one processor 602, a power source (not shown),a data storage 610, a system interface 612, a user interface 608, amemory 604, and one or more interconnection mechanisms 606. Thecontroller 600 may also include a power source (not shown) that provideselectrical power to other components. The at least one processor 602 maybe any type of processor or multiprocessor, and for example may includea digital signal processor. The at least one processor 602 is connectedto the other system components, including one or more memory devices 604by the interconnection mechanism 606. The system interface 612 couplesone or more sensors or components (e.g., actuator 210) to the at leastone processor 602.

The memory 604 stores programs (e.g., sequences of instructions coded tobe executable by the processor 602) and data during operation of thecontroller 600. Thus, the memory 604 may be a relatively highperformance, volatile, random access memory such as a dynamic randomaccess memory (“DRAM”) or static memory (“SRAM”). However, the memory604 may include any device for storing data, such as a disk drive orother nonvolatile storage device. Various examples may organize thememory 604 into particularized and, in some cases, unique structures toperform the functions disclosed herein. These data structures may besized and organized to store values for particular data and types ofdata.

Components of the controller 600 are coupled by an interconnectionmechanism such as the interconnection mechanism 606. The interconnectionmechanism 606 may include any communication coupling between systemcomponents such as one or more physical bus. The interconnectionmechanism 606 enables communications, including instructions and data,to be exchanged between system components of the controller 600.

The controller 600 can also include one or more user interface devices608 such as input devices, output devices and combination input/outputdevices. Interface devices may receive input or provide output. Moreparticularly, output devices may render information for externalpresentation. Input devices may accept information from externalsources. Examples of interface devices include keyboards, mouse devices,trackballs, microphones, touch screens, printing devices, displayscreens, speakers, network interface cards, etc. Interface devices allowthe controller 600 to exchange information and to communicate withexternal entities, such as users and other systems.

The data storage element 610 includes a computer readable and writeabledata storage medium configured to store non-transitory instructions andother data, and can include both nonvolatile storage media, such asoptical or magnetic disk, ROM or flash memory, as well as volatilememory, such as RAM. The instructions may include executable programs orother code that can be executed by the at least one processor 602 toperform any of the functions described here below.

Although not illustrated in FIG. 6, the controller 600 may includeadditional components and/or interfaces, such as a communication networkinterface (wired and/or wireless), and the at least one processor 602may include a power saving processor arrangement.

Having thus described several aspects of at least one implementation, itis to be appreciated various alterations, modifications, andimprovements will readily occur to those skilled in the art. Suchalterations, modifications, and improvements are intended to be part ofthis disclosure, and are intended to be within the spirit and scope ofthe disclosure. One or more features of any one example disclosed hereinmay be combined with or substituted for one or more features of anyother example disclosed. Accordingly, the foregoing description anddrawings are by way of example only.

The phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. As used herein, theterm “plurality” refers to two or more items or components. As usedherein, dimensions which are described as being “substantially similar”should be considered to be within about 25% of one another. The terms“comprising,” “including,” “carrying,” “having,” “containing,” and“involving,” whether in the written description or the claims and thelike, are open-ended terms, i.e., to mean “including but not limitedto.” Thus, the use of such terms is meant to encompass the items listedthereafter, and equivalents thereof, as well as additional items. Onlythe transitional phrases “consisting of” and “consisting essentiallyof,” are closed or semi-closed transitional phrases, respectively, withrespect to the claims. Use of ordinal terms such as “first,” “second,”“third,” and the like in the claims to modify a claim element does notby itself connote any priority, precedence, or order of one claimelement over another or the temporal order in which acts of a method areperformed, but are used merely as labels to distinguish one claimelement having a certain name from another element having a same name(but for use of the ordinal term) to distinguish the claim elements.

What is claimed is:
 1. A seat system for a vehicle, the systemcomprising: a seat; a support structure coupled to the seat that allowsthe seat to move about a first axis of a pivot; a first sensorpositioned to detect movement of the vehicle; a second sensor positionedto detect lateral acceleration of the pivot; an actuator configured tomove the seat; and a controller configured to: receive a first signalfrom the first sensor and a second signal from the second sensor;generate a command signal based at least in part on the first signal andthe second signal to instruct the actuator to position the seat at adesired command angle, wherein the controller is configured to reducethe second sensor signal by accelerations caused by steering the vehicleto correct the command signal; and provide a force command to theactuator to move the seat at the desired command angle based on at leastthe corrected command signal.
 2. The seat system according to claim 1,wherein the first signal includes at least a roll rate of the vehicleabout a second axis, and wherein the second signal includes a lateralacceleration of the pivot in a direction substantially perpendicular toa direction of travel of the vehicle.
 3. The seat system according toclaim 2, further comprising a third sensor positioned to detect a yawrate of the vehicle, and wherein the controller is configured togenerate the command signal according to:${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$wherein θ₁ is a rotation of the vehicle about the second axis, {umlautover (x)} is the lateral acceleration of the pivot, speed is a speed ofthe vehicle, yaw rate is the yaw rate of the vehicle, and L₂ is adistance between the first axis and a substantially center virtual pointof a payload supported by the seat system.
 4. The seat system accordingto claim 3, further comprising a global positioning system (GPS)configured to calculate the speed of the vehicle.
 5. The seat systemaccording to claim 3, wherein the second sensor is positioned at thepivot.
 6. The seat system according to claim 2, wherein the controlleris further configured to determine a frequency of the first signal andgenerate the command signal based on at least the first signal and thesecond signal and correct the command signal if the frequency of thefirst signal is greater than or equal to a reference threshold, andgenerate the command signal based on the first signal when the frequencyof the first signal is less than the reference threshold.
 7. The seatsystem according to claim 6, wherein the reference threshold includes afrequency between about 0.1 Hz and about 1.0 Hz.
 8. The seat systemaccording to claim 7, further comprising a third sensor positioned todetect a yaw rate of the vehicle, and wherein the controller isconfigured to generate the command signal according to:${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$wherein θ₁ is a rotation of the vehicle about the second axis, {umlautover (x)} is the lateral acceleration of the pivot, speed is a speed ofthe vehicle, yaw rate is the yaw rate of the vehicle, and L₂ is adistance between the first axis and a substantially center virtual pointof a payload supported by the seat system, when the frequency of thefirst signal is greater than or equal to the reference threshold.
 9. Theseat system according to claim 8, wherein the controller is configuredto generate the command signal according to:${\theta_{1} + {\left( \frac{L_{1}}{L_{2}} \right)\theta_{1}}},$ whereinθ₁ is the rotation of the vehicle about the second axis, L₂ is thedistance between the first axis and the substantially center virtualpoint of the payload, and L₁ is a distance between the second axis andthe first axis, when the frequency of the first signal is less than thereference threshold.
 10. The seat system according to claim 2, whereinthe second axis is substantially parallel to a direction of travel ofthe vehicle, and wherein the actuator is further configured to rotatethe seat in substantially an opposite direction from a rotation of thevehicle.
 11. A method of controlling seat movement in a vehicle, themethod comprising: receiving a first signal from a first sensorpositioned to detect movement of the vehicle; receiving a second signalfrom a second sensor positioned to detect lateral acceleration of apivot including a first axis about which a support structure coupled toa seat allows movement of the seat; generating a command signal based atleast in part on the first signal and the second signal to instruct anactuator to position the seat at a desired command angle, whereingenerating the command signal includes reducing the second sensor signalby lateral accelerations caused by steering the vehicle to correct thecommand signal; and providing a force command to the actuator to movethe seat at the desired command angle based on at least the correctedcommand signal.
 12. The method according to claim 11, wherein the firstsignal includes at least a roll rate of the vehicle about a second axis,and wherein the second signal includes a lateral acceleration of thepivot in a direction substantially perpendicular to a direction oftravel of the vehicle.
 13. The method according to claim 12, furthercomprising receiving a third signal from a third sensor positioned todetect a yaw rate of the vehicle, and wherein generating the commandsignal includes generating the command signal according to:${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$wherein θ₁ is a rotation of the vehicle about the second axis, {umlautover (x)} is the lateral acceleration of the pivot, speed is a speed ofthe vehicle, yaw rate is the yaw rate of the vehicle, and L₂ is adistance between the first axis and a substantially center virtual pointof a payload supported by the seat.
 14. The method according to claim13, further comprising receiving the speed of the vehicle from a globalpositioning system (GPS).
 15. The method according to claim 12, furthercomprising determining a frequency of the first signal, and whereingenerating the command signal based on at least the first signal and thesecond signal includes generating the command signal based on at leastthe first signal and the second signal when a frequency of the firstsignal is greater than or equal to a reference threshold, and the methodfurther comprises generating the command signal based on the firstsignal when the frequency of the first signal is less than the referencethreshold.
 16. The method according to claim 15, wherein the referenceincludes a frequency between about 0.1 Hz and about 1.0 Hz.
 17. Themethod according to claim 16, further comprising receiving a thirdsignal from a third sensor positioned to detect a yaw rate of thevehicle, and wherein generating the command signal based on at least thefirst signal and the second signal when the frequency of the firstsignal is greater than or equal to the reference threshold includesgenerating the command signal according to:${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$wherein θ₁ is a rotation of the vehicle about the second axis, {umlautover (x)} is the lateral acceleration of the pivot, speed is a speed ofthe vehicle, yaw rate is the yaw rate of the vehicle, and L₂ is adistance between the first axis and a substantially center virtual pointof a payload supported by the seat.
 18. The method according to claim17, wherein generating the command signal based on the first signal whenthe frequency of the first signal is less than the reference thresholdincludes generating the command signal according to:${\theta_{1} + {\left( \frac{L_{1}}{L_{2}} \right)\theta_{1}}},$ whereinθ₁ is the rotation of the vehicle about the second axis, L₂ is thedistance between the first axis and the substantially center virtualpoint of the payload, and L₁ is a distance between the second axis andthe first axis.
 19. A vehicle seat comprising: a seat configured to moveat a command angle about a first axis of a pivot relative to asubstantially horizontal orientation; and a controller configured to:receive a first signal of detected movement of a vehicle and a secondsignal of detected lateral acceleration of the pivot; and generate acommand signal based on at least the first signal and the second signalto instruct an actuator to position the seat at a desired command angle,wherein the controller is configured to reduce the second signal bylateral accelerations caused by steering the vehicle to correct thecommand signal.
 20. The vehicle seat of claim 19, wherein the controlleris further configured to provide a force command to move the seat at thedesired command angle based on at least the corrected command signal.21. The vehicle seat of claim 19, wherein the first signal includes atleast a roll rate of the vehicle about a second axis, and wherein thesecond signal includes a lateral acceleration of the pivot in adirection substantially perpendicular to a direction of travel of thevehicle.
 22. The vehicle seat of claim 21, wherein the controller isfurther configured to receive a detected yaw rate of the vehicle, andwherein the controller is configured to generate the command signalaccording to:${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$wherein θ₁ is a rotation of the vehicle about the second axis, {umlautover (x)} is the lateral acceleration of the pivot, speed is a speed ofthe vehicle, yaw rate is the yaw rate of the vehicle, and L₂ is adistance between the first axis and a substantially center virtual pointof a payload supported by the vehicle seat.
 23. The vehicle seat ofclaim 21, wherein the controller is further configured to determine afrequency of the first signal and generate the command signal based onat least the first signal and the second signal if the frequency of thefirst signal is greater than or equal to a reference threshold, andgenerate the command signal based on the first signal when the frequencyof the first signal is less than the reference threshold.
 24. Thevehicle seat of claim 23, wherein the reference threshold includes afrequency between about 0.1 Hz and about 1.0 Hz.
 25. The vehicle seat ofclaim 24, wherein the controller is further configured to receive adetected yaw rate of the vehicle, and wherein the controller isconfigured to generate the command signal according to:${\theta_{1} + \frac{\int{\int\left( {\overset{¨}{x} - \left( {{speed}*{yaw}\mspace{14mu}{rate}} \right)} \right)}}{L_{2}}},$wherein θ₁ is a rotation of the vehicle about the second axis, {umlautover (x)} is the lateral acceleration of the pivot, speed is a speed ofthe vehicle, yaw rate is the yaw rate of the vehicle, and L₂ is adistance between the first axis and a substantially center virtual pointof a payload supported by the vehicle seat, when the frequency of thefirst signal is greater than or equal to the reference threshold. 26.The vehicle seat of claim 25, wherein the controller is configured togenerate the command signal according to:${\theta_{1} + {\left( \frac{L_{1}}{L_{2}} \right)\theta_{1}}},$ whereinθ₁ is the rotation of the vehicle about the second axis, L₂ is thedistance between the first axis and the substantially center virtualpoint of the payload, and L₁ is a distance between the second axis andthe first axis, when the frequency of the first signal is less than thereference threshold.